Furnace.



F. DITCHFIELD.

` FURNACE.

APPLICATION FILED MAR. 27| 1915. EENEWED MAR. 24| 1916.

1,182,256. Patented May 9,1916.

2 SHEETS-SHEET l.

F. DITCHFIELD.

FURNACE. APPLICATION FILED MAR. 27,1915- RENEWED MAR. 24| |916. y 1,182,256. Patented May 9,1916.

2 SHEETS-SHEET 2.

A:FRANK DITCHFIELD, F MONTREAL, QUEBEC, CANADA.

FURNACE.

Specification of Letters Patent.

Application led. March 27, 1915, Serial No. 17,387. Renewed March 24, 1916. Serial No. 86,501.

a'citizen of Ithe Dominion of Canada and resident of the city of Montreal, in. the

Province of Quebec and Dominion of` Canada, have invented certain new and useful Improvements in Furnaces, of which the following is a full, clear, and exact description. 4

This invention relates to improvements in furnaces, and more particularly to that class of furnace adapted fory heat treating metal articles, or for baking or glazing pottery or the like.

The object of the invention is to provide a continuous furnace, thatr is to say, one in rwhich the material to be treated enters one end of the furnace and passes through and out at the* other end of the furnace, articles removed at the discharge end being replaced bythe insertion of fresh articles at the mouth of the furnace.

A further object is to provide a furnace having an endless conveyer located externally of the furnace, and adapted to carry the articles through the furnace.

A still further object is to provide a furnace with conveying system so arranged that each article will be free of all load except dit its own weight and exposed over its entire surface to the heat.

Another object is to provide a furnace of simple, durable and inexpensive construction so arranged that should the air supply be cut ed, the unburned fuel will not come in contact with the articles in the furnace for treatment.

In the present invention, the furnace has been arranged to overcome the disadvantages outlined in the preceding paragraph. The conveyer is mounted above the furnace where it is cool, and therefore capable of being operated at small cost. The articles are suspended from the conveyer by hooks passing through a narrow slot formed longitudinally in the top'of the furnace, this slot being closed by the conveyer. The burners and combustion chambers are located below the hearth, so that in the event of failure of the air supply, excess fuel in liquid form will merely puddle in the combustion chamber and will not enter the furnace proper. The articles to be treated are suspended in the middle of the furnace and are therefore bathed over their entire surface in the heat or ame. Such an arrange The furnace 'shown in the drawings is Patentedltllay 9,' 11916.

particularly ldesigned for the treatment of Y shrapnel shells or cartridge cases, but it must be understood that the invention is not limited to the precise form shown, as changes may be made in the shape and arrangement of the furnace to Vadapt it to the treatment of various other articles.

In the drawings which illustrate the invent1on:-Figure 1 is a side 'elevation of the furnace. Fig. 2 is a horizontal sectional view on the line 2-2, Fig. 1, and shows the arrangement of burners. Fig. 3 isa vertical cross section on the line 33, F 1g. l. F ig. 4 is a fragmentary plan View of the conveyer. Fig. 5 is a fragmentary sectional View of the recess in each link and its manner of engagement with the sprocket teeth. Referring more particularly to the drawings, 11 designates a foundation upon which stanchions 12 are mounted at suitable intervals. Between the stanchions, wall plates 13 are provided which with the stanchions form the casing of the furnace.

The stanchions on opposite sides of the furnace are connected over the top by beams 14C, to the upper and lower sides of which Z bars 15 are attachedin pairs to form a track for the conveyer chain.

Within the casing is the furnace proper, designated "16, having a floor 17 side walls 18, and an arched top 19. Burners 2O are arranged alternately on opposite sides of the i furnace and communicate with the furnace through ducts 21 passing under the floor across the furnace and opening into the furnace through the floor at the opposite side thereof from the burners. These ducts are of such size to form mixing chambers for the air and fuel.

A. longitudinal slit 22 is formed in the roof extending from end to end of the furnace. Under ordinary circumstances, the presence of this slit would destroy the strength of the arched roof. To overcome this, cheek plates 23 are provided on each side of the slot held in place by bolts 24, passing through the arch and the stanchions and wall plates 13. rlhese cheek plates have exactly the same effect as the key of the arch, so that the stability of the roof is not impaired. 'llo further strengthen the structure, .the

` stanchions and if Vdesired the wall plates are provided c o n the ends of these brackets.

An endless conveyer chain 27 is provided running over sprockets 28 mounted `on the ends of the conveyer frame 15. This chain consists'of a plurality of links 29 fiat on one side which may be termed the outer side.

The links are pivotally connected togetherA by pins 30 which extend a `considerable distance beyond the links and arel provided with .small flanged rollers or wheels 31, adapted to travel on the Z bars ofthe frame. vEach link is -thus supported at both ends and becomes a wheeled carriage movable with a minimum of friction on the track or frame. The width of the links is slightly greater thanthe width of the slot- 22 atl its top, and the device is adjusted so that the chain just bears upon the upper edges of the cheek slot 22. The weight of the chain and any load carried thereby is, however, really sustained by the rollers traveling on the Z bars. The bearing of the chain on the cheek plates or the amount of clearance to a minute fraction of an inch may be regulated by` inserting shims 142L between the cross beams 14 and stanchions 12, thus raising or loWer-'\ ing the whole conveyer as required. On the ,flat or outer side of thelinkyan eye 32 is v formed which occupies the upper part of the sprockets l28.

at the ends is effected by the doors 35,

.the slot 22, and from which depends a hook or sling 33, reaching down-through the slotl into the furnace and supporting the articles to be treated. Each link has formed therein,

on the face opposite its eyebearing face a recess 34 for engagement with the teethof The closing of this slot which extend right' Yup to the lower 'Z bars, as

l shown in Fig. 1.

At the `entranceJ end of the furnace, a

cooling tank 36 with arrangements for a continuous supply of cooling liquid is provided. A suitable chute 37 extends from the conveyer tothe tank. At the opposite y simple. The

or discharge end ofthe furnace, the

' sprocket 28 is driven by any suitable means,

such as a motor 38. Vents 39 may be provided in the roof of the furnace, ifdesired, and also pyrometer openings 40 in the sides.

The operation lof the device is extremely v furnace is controlled from ,the discharge end. The operator irst opens lthe doors 4at both ends simultaneously, and

4then starts the conveyer, which operates to draw out one batch of articles from the fur-V nace, at the Isaine time carrying in a fresh batch at vthe entrance, and -movingy all batches in 'the furnace `along one'step toplates and forms a cover' for the' ward the discharge Iend. The furnace is then closed. 1t will be noted that the conveyer frame extends beyond thefurnace at each'end, so that between operations of the` conveyer, a fresh batch of articles may be suspended of the furnace, and at the discharge end of the furnace the completed batch of articles will remain suspended fromV the conveyer, and may be easily removed as the conveyer is now stationary. When the batch is removed, the hooks or slings 33v are thrown on to the top of the4 conveyer, so that as the conveyer moves, they are gradually carried` a fresh batch of articles from the conveyer.,

The cooling is effected merely by radiation of the heat yin the surrounding air. When the hooks emerge from the furnace,

' they are of course at high temperature and are handled with tongs. When the suspended article is removed, the hooks are disconnected from the chain'andthrown loose on the top of the conveyer by' the operator at this end. The radiation of heat during the travel to the'front end of the furnace has an annealing effect on the hooks, so that when they are quenched, the metal will not become crystallized or twisted.

It will be clearly seen that the heat 4or iame .of the furnace will have a swirling motion, as indicated by the arrows, which will tend to carry the flame past the mouth of the slot 22. As this slot is entirely closed at the top, it cannot actas a flue to draw up the heat, and is ,therefore filled with dead air, possibly under very slight pressure, which prevents the entrance of the heat. In any event, theslot is so deep and narrow that the conveyer remains quite cool. The suspension of the articles to be treated in rthe middle of .the furnace permits the swirling flame topass all around' and bathe the entire surface of each article, thus insuring a uniform heating. If small articles are heated in pans, the same practice istrue, as the flame passes all 'around the pan." The conveying means being cool, the `furnace may be operated much more eiiciently andv economically than is possible with thevtypes at'present in general use. ln the event of gas accumulating in the furnace,

ence ofl the longitudinal slot 22, as the presfrom the 'conveyer at the entrance I which i would tend to cause an explosion, damage to;

.the furnace will be prevented bythe presby the lift of the conveyer chain. Inthe treatment of hollow articles, such as cartridge cases, shrapnel shells, or pottery, each aisance article or group of articles may be independently supported, and will have no load to sustain beyond its own weight, thus largely preventing distortion and warping. In the case of heavy yarticles such as blooms or billets of steel, or large objects like guns, re quiring tempering or annealing, the furnace may be operated more rapidly and economically than is ordinarily possible. owing to the reduction of friction.

It is obvious that changes in the shape and arrangement of the furnace will be nec essary according to the character of the material to be treated, but that the principle wilLremain the same whether the furnace is designed and used for heating steel billets or baking bread.

Having thus described my invention, what I claim is l. In a continuous furnace, a roof having a longitudinal slot therein, a casing for the furnace, brackets from said casing extending inwardly to the slot, cheek plates for the slot bearing against said brackets, and bolts supporting the cheek plates from the casing and sustaining the load of the roof.

2. In a continuous furnace, a roof having a longitudinal slot therein, a casing for the furnace, cheek plates lining said slot and supported above the roof from the casing. an adjustable conveyer frame mounted on the casing, a chain traveling on said frame and bearing on the cheek plates to form a closure for the slot, said chain comprisinga plurality of links, pivots connecting said links, rollers mounted on said pivots traveling on the conveyer frame and taking the load of the conveyer chain o the cheek plates.

3. In a furnace, a roof having a longitudinal slot therein, and tension members in the roof extending from the slot to the sides of the furnace and supporting the roof.

l. In a furnace, a roof having a longitudinal slottherein, a casing for the furnace, tension members and tension means extending from the slot to the sides of the furnace arranged to perform the function of an arch key stone.

5. In a furnace, a roof havinga longitudinal slot therein, a casing, tension members binding each half of the roof to the casing whereby each half of the roof is self-supporting, and transverse connections between the sides of the casing above the roof slot.

6. In a furnace, a roof having a longitudinal slot therein, side plates forming a casing, rigid arms projecting inwardly from the casing and extending through the roof to the slot, cheek `plates bearing against the arms and against the roof at the edge of the slot, and tension members forming a roof supporting truss.

In witness whereof, I have hereunto set my hand, in the presence of two witnesses.

'FRANK DITCHFIELD.

IVitnesses SMR. W. ALLEN, G. M. MORELAND. 

